Imprinting machine with controlled imprinting force



April 5, 1966 G. N. RILEY 3,244,096

IMPRINTING MACHINE WITH CONTROLLED IMPRINTING FORCE Filed Sept. 15, 1964 2 Sheets-Sheet 1 5/ fi ww I INVENTOR 7 V d'ilbeli' NEL'Ze 1 25 BY PM fivToauey April 5, 1966 e. N. RILEY 3,244,096

IMPRINTING MACHINE WITH CONTROLLED IMPRINTING FORCE Filed Sept. 15, 1964 2 Sheets-Sheet 2 aya INVENTOR.

HTToR United States Patent I ware Filed Sept. 15, 1964, en. No. 396,614 7 Ciaims. or. 101-297 This invention pertains to imprinting machines. More particularly, it deals with controlling the imprinting force in such machines.

In various applications, imprinting machines are called upon to operate on documents having considerable variation in thickness. One example of such a machine is a postage meter, which imprints postage and other indicia on stuffed envelopes. The stuffed envelopes will vary greatly in thickness, depending on their contents. To accommodate this range of thicknesses, prior art machines have included in their drive train something in the nature of a yieldable coil spring. Then, when the platen member or the imprinting member, whichever is the movable 'driven element, is driven for the imprinting stroke, as soon as it moves into pressing relation with the other member, the coil spring will be compressed and the envelope will be imprinted as the driven member completes its imprinting stroke. With such an arrangement, however, there is inherently a considerable variation in the printing force, depending on the envelope thickness. The operating stroke of the movable driven member must be sufiiciently long to compress the coil spring enough to develop the desired imprinting force for the thinnest envelope to be handled. However, for a thicker piece, the spring compression will start at an earlier point in the imprinting stroke but will continue to the same ultimate point in the stroke, resulting in a greater degree of spring compression-and therefore a larger imprinting forcethe thicker the work piece.

This has various objections and disadvantages. The minimum force developed, i.e., for the thinnest work piece, is all that is actually needed for any work piece. Thus, the larger imprinting force generated for thicker pieces is unnecessary. Therefore, the energy required to operate the machine is greater than it need be for suitable imprinting. If the machine is motor driven, a larger and more expensive motor must be used. If it is hand operated, the operator must expend extra energy. In either case, the parts of the machine are subjected to greater wear. Further, the imprint will not be uniform but will vary in intensity and definition depending on the work piece thickness.

It is therefore an object of the present invention to provide a novel imprinting machine.

It is a further object to provide an imprinting machine which will imprint work pieces of different thickness with no more than the intended desired printing force regardless of the work piece thickness.

It is a further object to minimize the operating energy requirement of an imprinting machine.

- It is a further object to provide an imprinting machine of reduced size.

v It is a further object to provide an imprinting machine in which the imprint produced thereby is substantially uniform regardless of the thickness of the work piece.

It is a furtherobject to provide an economical, inexpensive mechanism for achieving the foregoing objects.

The above, and other objects, advantages, and features of the invention will be apparent to those skilled in the A, art from the following detailed description of a preferred embodiment of the invention, when read in conjunction with the accompanying drawings, in which:

3,244,096 Patented Apr. '5, 1966 FIG. 1 is a top plan view of the imprinting machine.

FIG. 2 is a sectional view, taken on line 2-2 of FIG. 1,

of the machine in normal, unoperated condition.

FIG. 3 is a sectional view taken on line 3--3 of FIG. 2.

FIG. 4 is a view similar to FIG. 2, showing the mechanism in operated position.

FIG. 5 is an enlarged fragmentary detail view showing a portion of the means for driving the platen, just as the platen unit commerces pressing the envelope against the die plate.

FIG. 6 is a view similar to FIG. 5 showing the relative position of the parts just as the maximum imprinting force has been attained.

FIG. 7 is a similar view showing the actuator lever arm at the top of its forward or imprinting stroke for a thick envelope.

Referring now to the drawings, the reference numeral 1 designates the base plate of the machine. Mounted on base plate 1 is an electric motor 2 operable to drive a main drive shaft 3 through a selectively engageable and disengageable clutch 4. The motor and clutch are controlled by any suitable conventional means to elfect a single full revolution of shaft 3 in each cycle of operation of the machine.

The imprinting means itself comprises a downwardly facing imprinting or die plate 5 secured to the machine framing 6; and a cooperable vertically movable platen unit 7 normally resting on fixed upstanding posts 8. The die plate is inked inany suitable fashion. Platen unit 7 comprises a relatively firm but yieldable block 7a of rubber or other elastomeric material fixed to an underlying rigid steel plate 71).

Each stuffed envelope E, or other work piece, to be imprinted, is placed on the platen unit 7. By the novel means to be described shortly, the platen unit is driven upwardly to press the work piece against die plate 5 to be imprinted; and the platen unit is then returned downwardly to home position.

The platen unit 7 is disposed between and adapted to be driven by a pair of similar platen actuating lever arms 11 each rockably supported by a stub shaft 12 between a pair of closely spaced upstanding support plates 13 mounted on base plate 1. Opposed pins 14 rigid with the respective opposite sides of the platen unit bottom plate 71: extend laterally outwardly through elongated slots 15 provided in the forward ends of the respective actuating arms 11. Each pin 14 carries a roller 16 inwardly of the related actuating arm 11, through which rollers the platen unit 7 is driven by the arms.

Identical cams 17 are provided fast on drive shaft 3 for controlling cyclic rocking movement of actuating arms 11. Each cam 17 includes an outer cam surface 17a engaged by a first follower wheel 18 mounted at the rear end of the related arm; and an inner cam surface engaged bya second follower wheel 19 carried by an offset bracket 26 secured to the arm. Compression springs 21 impose a counterclockwise bias (FIG. 2) on the actuating arms.

On each cycle of rotation of drive shaft 3, cam 17 will first rock arms 11 clockwise to their FIG. 4 position, and then return them to their normal home or full cycle position of FIG. 2.

The means whereby power is transmitted to the platen unit 7 from the actuating arms 11, and is controlled, will now be described. Pi'votally mounted at the inside forward end of each actuating arm on a pin 22 is a small rocker cam 23. Each rocker cam is at all times biased forwardly into engagement with the related roller 16 by an elongated leaf spring 24. The rearward end of each leaf spring is rigidly fastened to the associated actuating arm 11 by being pinned to a plate 25 riveted to the arm.

3 The forward free end of each leaf spring 24 is seated in the base of a recess 26 formed in the rear edge of the related rocker cam 23.

The forward edge 27 of each rocker cam (see FIGS. 5-7), which edge cooperates with roller 16, includes a rapidly rising edge portion 27a, which intersects a longer and less steep edge portion 27b. Leaf springs 24 are of sufficient length that they are at all times held in a bowed or charged condition to maintain the rocker cam forward edge 27 in engagement with rollers 16.

The normal unoperated position of the parts is as shown in FIGS. 2 and 5, with the platen pins 14 at the top of the actuating arm slots 15, and rollers 16 engaging the rocker cam edges 27 just at the junction of the two intersecting cam edge portions 27a and 27b.

In a cycle of operation, actuating arms 11 first swing clockwise carrying the platen unit 7 therewith through the engagement of rollers 16 with the rocker cam edges 27. At this juncture, it should be noted that the relevant parameters of the mechanism e.g. the slope of the rocker cam edge portions 27a and 21712, the physical characteristics of leaf springs 24, etc. are so selected that anything in excess of the desired predetermined imprinting force-- as reflected through rollers 16 to the rocker cam edge 27 engaged there'bywill cause the. rollers to swing the cams rearwardly so that the rollers now ride on the lower edge portions 27b, of the rocker cams (see FIG. 6). However, any lesser imprinting force will be insufficient to cause the rollers to swing the rocker cams rearwardly against the urge of leaf springs 24.

As the rising platen unit 7 and the envelope E thereon commence pressing against the die plate 5, the imprinting force will start to build up. When the predetermined imprinting force is attained, rollers 16 will push rocker cams 2-3 rearwardly from the latters normal enabled (or effective) coupling position of FIG. 5 to their disabled (or ineffective) position of FIG. 6, the platen unit now being stationary. This operation comprises an initial slight counterclockwise rocking of the rocker cam-s 23, and. increased bowing of leaf springs 24. Rollers 16 will remain resting substantially on the intersection of rocker cam edge portions 27a and 27b during this initial rocking of the cams since the latter movement lowers this intersection. Then, as the actuating arms 11 continue rising as permitted by their slots 15, the rollers will, in a relative sense, ride down over the junction of the rocker cam edge portions 27a, 27b and onto edge 2712 (see FIG. 6) causing additional bowing of springs 24. This transtional swinging movement of the rocker cams 23 to their disabled or ineffective position of FIG. 6 will of course occur earlier the thicker the envelope E to be imprinted. Further, it will occur quite rapidly as soon as the predetermined maximum printing force is reached, for the reason that each bowed leaf spring functions as a buckled column, wherein additional buckling occurs rapidly with the application of a small additional force.

After the rocker cams 2 3 have been swung rearwardly to ineffective position yas just described, their forward edge portions 271), which are engaged by rollers 16, are now substantially parallel to slots 15. Cam-s 26 are therefore now substantially ineffective to transmit a vertical force component to platen unit 7 through rollers 16. Essentially, only a minimal frictional load is imposed on the system by the platen unit 7, which will remain stationary as the actuator arms 11 continue upwardly a short distance to complete their forward stroke. As stated above, for thicker pieces of mail the imprinting .per se and disablement of rocker cams 23 will occur earlier in the stroke, resulting in a greater upward movement of the actuator arms relative to the now stationary platen unit (see for example FIG. 7).

In the second half of the cycle, actuator arms 11 will be rocked counterclockwise back to home position (FIG. 2), and the platen unit 7 will descend therewith until it 4. engages posts 8 and thereby comes to rest. However, the downward return movement of arms 11 continues enough to allow rocker cams 23 to assume their normal enabled or effective driving relation with rollers 16. Thus, at the end of the cycle, the parts are once again in the normal full cycle position of FIGS. 2 and 5.

If the envelope E sticks to the die plate 5 in the imprinting operation, vertically offset forwardly extending stripper fingers 2 8 of the actuator arms 11 will push it free on the return stroke. Slots 3:1 in the machine framing 6 allow the fingers 28 to pass therethrough. A deflector plate 32 (:FIG. 2) prevents the operator from inadvertently placing the envelope to be imprinted a'bove strippers fingers 28. Additional guiding and support for the vertical movement of platen unit 7 is provided by an arm 29 pivoted at its rear end on the machine framing and at its forward end to a central depending lug 33 (FIGS. 1, 3) of the platen unit.

As just described, the present arrangement provides that the imprinting force will fall off rapidly as soon as it has reached the predetermined maximum value. This is the preferred situation since the energy which would otherwise be used for a greater imprinting force is thus made immediately available for other purposes from the total effective energy output of motor 2. If desired for any reason, throughout the remainder of the forward imprinting stroke of arms 11 the imprinting force level can be held at the maximum value, or fall off at any desired slower rate, by providing the appropriate slope or contour for the rocker cam edges 27.

It will be understood that numerous changes can be made in the arrangement, shape, size, relative movement of parts, etc. of the mechanism without departing from the principles of the invention and its features. Accordingly, it is intended that the foregoing disclosure of a preferred embodiment be illustrative only and not limitative of the following claims.

I claim:

1. In a machine for imprinting documents of variable thickness:

an imprinting member;

a platen member cooperable therewith;

at least one of said members being arranged for imprinting movement toward the other;

means for driving said one member toward the other to imprint a document adapted to be placed therebetween with a substantially constant maximum imprinting force of a given magnitude independent of the thickness of said document; said driving means comprising:

(a) actuating means comprising a driven movable drive link on which said one member is mounted for movement into and out of printing contact with said other member, and

(b) means coupling said actuating means to said one member said coupling means comprising (1) cam means having a recessed portion and being rotatably mounted on said movable drive link for movement from an effective position wherein said first member engages said recessed portion so as to be driven into printing contact with said other member, and to an ineffective position wherein said first member is disengaged from said recessed portion and said cam does not provide any substantial driving force to said first member, and

(2) means to automatically maintain said cam means in said effective position when the imprinting force is less than said maximum imprinting force and to permit said cam means to move to said ineffective position when said maximum imprinting force is exceeded.

2. The combination according to claim 1, wherein:

said driving means to maintain said cam means in said elfective position further includes elongated spring means for transmitting force along its length to said 6. The combination according to claim 5, wherein: said drive link constitutes at least one rockable lever. 7. The combination according to claim 6, wherein: the opposite end of said leaf spring is rigidly connected said cam means and leaf spring are so arranged that the References Cited by the Examiner UNITED STATES PATENTS latter is automatically adjusted from a first, bowed, 10 g i charged condition of given curvature to a second, 1 1/1923 gi -g more bowed condition of greater curvature 1n re- 1:796:327 3/1931 Gounick et a1 sponse to movement of said cam means from its effective to its inefiective positions. 5. The combination according to claim 3, wherein: one end of said leaf spring freely engages said cam means.

5 ROBERT E. PULFREY, Primary Examiner.

WILLIAM B. PENN, Examiner. 

1. IN A MACHINE FOR IMPRINTING DOCUMENTS OF VARIABLE THICKNESS: AN IMPRINTING MEMBER; A PLATEN MEMBER COOPERABLE THEREWITH; AT LEAST ONE OF SAID MEMBERS BEING ARRANGED FOR IMPRINTING MOVEMENT TOWARD THE OTHER; MEANS FOR DRIVING SAID ONE MEMBER TOWARD THE OTHER TO IMPRINT A DOCUMENT ADAPTED TO BE PLACED THEREBETWEEN WITH A SUBSTANTIALLY CONSTANT MAXIMUM IMPRINTING FORCE OF A GIVEN MAGNITUDE INDEPENDENT OF THE THICKNESS OF SAID DOCUMENT; SAID DRIVING MEANS COMPRISING: (A) ACTUATING MEANS COMPRISING A DRIVEN MOVABLE DRIVE LINK ON WHICH SAID ONE MEMBER IS MOUNTED FOR MOVEMENT INTO AND OUT OF PRINTING CONTACT WITH SAID OTHER MEMBER, AND (B) MEANS COUPLING SAID ACTUATING MEANS TO SAID ONE MEMBER SAID COUPLING MEANS COMPRISING (1) CAM MEANS HAVING A RECESSED PORTION AND BEING ROTATABLY MOUNTED ON SAID MOVABLE DRIVE LINK FOR MOVEMENT FROM AN EFFECTIVE POSITION WHEREIN SAID FIRST MEMBER ENGAGES SAID RECESSED PORTION SO AS TO BE DRIVEN INTO PRINTING CONTACT WITH SAID OTHER MEMBER, AND TO AN INEFFECTIVE POSITION WHEREIN SAID FIRST MEMBER IS DISENGAGED FROM SAID RECESSED PORTION AND SAID CAM DOES NOT PROVIDE ANY SUBSTANTIAL DRIVING FORCE TO SAID FIRST MEMBER, AND (2) MEANS TO AUTOMATICALLY MAINTAIN SAID CAM MEANS IN SAID EFFECTIVE POSITION WHEN THE IMPRINTING FORCE IS LESS THAN SAID MAXIMUM IMPRINTING FORCE AND TO PERMIT SAID CAM MEANS TO MOVE TO SAID INEFFECTIVE POSITION WHEN SAID MAXIMUM IMPRINTING FORCE IS EXCEEDED. 